No German here so I probably missed a lot of the subtext. The movie reminded me of that book on Hitler's last days, by Hugh Trevor Roper. I guess reading that or even Joaquim Fest's original (in translation) would help understand more.

I Have Albert Speer's, "Inside the Third Reich" on my reading list. It should prove interesting. Undertag had him shown as a pretty levelheaded guy but one who did not want to know too much.